1. Field of the Invention
The present invention relates to a device for incrementally identifying the position of a magnetic levitation vehicle, particularly having a long stator motor, comprising at least one coded measuring strip which extends in the direction of travel with a fixed positional allocation relative to the stator winding, and comprising a sensor system disposed on the vehicle and comprising one or more sensors arranged with a spacing in the direction of travel for detecting the coding.
2. Description of the Prior Art
In order to stabilize the propulsive forces in a synchronous elongate stator motor, it is necessary to acquire information concerning the relative position of the vehicle-related excitation field and the stator winding distribution in order to be able to define the phase relation of the thrust-creating stator ampere turns per centimeter. Beyond this, information is also required concerning the absolute vehicle position as well as the vehicle velocity. It is therefore necessary to control the mechanical air gap between the portative magnet and the rail.
It is known in the art, given a synchronous linear motor having path-controlled excitation, to dispose a coded measuring strip along the stator, this lying in the area of sensors whose measuring signals supply reference values for the excitation current (in this connection see the German published application No. 21 16 724). The sensors are disposed in the area of the exciting winding so that the measured signals are influenced by the induction currents.
An inductive measuring system is known in the art for measuring and controlling the mechanical air gap between the magnet and the support rail, the measuring system being disposed directly between the magnet and the rail, as in the German published application No. 28 03 877. This measuring system is likewise influenced by the magnets.
The continuous identification of absolute vehicle position, i.e. the location of the vehicle along the rail, has heretofore occurred by way of integrating the path information. Despite reliable integration methods, however, such a position identification leaves much to be desired because errors cannot be excluded or, respectively, because the positional information must be reliably stored.